Among the effects of global warming, increased drought, a higher risk of flooding and sewage water flowing directly into rivers after heavy rain are particularly challenging for cities. There is often little undeveloped space where that water can be collected and stored in nature. The WETSPA-Urban model developed by Dr Nahad Helmi for his doctorate in engineering at the VUB is helping cities to carry out cost-benefit analyses of possible precautionary measures, such as more green space, and shows the areas where these are best implemented.
The WETSPA-Urban model (Water and Energy Transfer between Soil, Plants and Atmosphere) was developed within VUB’s hydrology research group and combines data on natural runoff with simulations of urban drainage for sewers and a hydrologically detailed infiltration model. The tool made maps with recommendations. The simulations with these recommendations show that a smart application of green infrastructure has a large positive impact, especially with smaller, more frequent floods. In the PhD, the model is applied to Roodebeek in Brussels. By applying low-impact development to 16% of the Roodebeek sub-basin, one of the most urbanised parts of the Woluwe sub-basin, flooding can be reduced by 85%.